OK, lets put it like this......... How can a gallon of water produce enough hydrogen gas to operate an automobile engine at highway speeds? Even if you could break down the H2O fast enough for the engine to suck up.

Guys the trouble with hydrogen isn't the difficulty of extracting it, that'* easy. The problem is that even electolysis takes a ton of energy for large amounts of the gas. Not to mention that electrolysis is slow...
Then there'* the storage tanks. You need lots of hydrogen to go anywhere, and it needs to be stored at high pressure. You can have a tank completely filled with hydrogen, but if it'* not pressurized, it won't come out at all. So you have to pressurize it. Alot. That builds heat, that has to be extracted in a multi-stage process. Squeeze, freeze, squeeze, freeze. Takes a lot of energy. Also takes large apparatus called multi-stage refrigerators. Not something you could keep at home. Also to expensive for your neighborhood filling station.
Continue in this vein, and you'll come to realize that you'd need a system just as extensive as that for distributing our various petroleum products around the country, but massively more complicated. The pipes would have to be just as heavy as the tanks used to store the liquified hydrogen. This means you'd have to spend several TRILLION dollars to construct all the neccessary infrastructure, at a conservative guess. And just imagine replacing all those fuel tankers on the road with liquid hydrogen tankers...imagine just ONE having a wreck...now look up the stats for yearly fuel tanker clean-up numbers...
It'* just not practical.
Oh, and BTW, a badly tuned hydrogen motor would put out unbelievably nasty chemicals, hydrogen sulfide being the least of your worries...

Good show BMW. Makes great sense to put this technology in a car large enough to have room for everything else as well. I would love for this technology to become available to the mainstream drivers.